What Is The Difference Between Sour and Wild Ales?

Thanks to a short article by the Urban Beer Nerd, I went on my own little journey to determine what the defining characteristics of sour and wild ales are and should be.

“In my quest to try every sour beer I can get my mitts on, I’ve encountered quite a few “wild ales,” some of which were sour and many that were not. I also read the word “Brettanomyces” or “Brett” a lot. Brett is a wild yeast strain used in many wild and sour ales.

At first, I assumed that sour beers and wild ales were one in the same, but after tasting many wild ales with Brett that were not at all sour, I did some research to determine the difference between the two.

First of all, there are no concrete definitions of sour beer and wild beer. But here’s what The Oxford Companion to Beer says on the subject:

“The development, largely by American craft brewers, of entirely new categories of beer [that use wild yeast and/or bacteria] during the past decade, has resulted in the need for a new nomenclature to describe them. This nomenclature is surely unsettled, but the two terms in general use are ‘sour beer’ and ‘wild beer.’ ‘Wild beer’ is generally used to describe any beer that displays earthy characteristics of Brettanomyces yeast strains, regardless of whether the beer is a light golden ale or a strong dark stout. If the brewer adds acidifying bacteria to the beer, it is termed a ‘sour beer.’ If both Brettanomyces character and bacterial acidity are in evidence, then the beer is generally deemed to fit both categories.”

So, to sum that up. Beers with funky, Brett character but no acidity from added bacteria are commonly referred to as “wild ales,” and they are not necessarily sour. If a brewer opts to add bacteria to a beer made with wild yeast the beer will take on an acidic, sour flavor. These beers are called sour beers. Wild ales can be sour, but not all of them are. The difference between the two is the addition of bacteria during the barrel aging process—the two most common bacteria used in the process are Lactobacillus and Pediococcus.

There you have it, wild beers are not necessarily sour beers; some just taste “funky” due to the wild yeast used during fermentation. And many sour beers, but not all, can be called wild, because they use wild yeast, as well.”